Asphalt composition containing a fatty ester and a process of making it



United States Patent ASPHALT COMPOSITION CONTAINING A FATTY ESTER AND Araocass or MAKING 11 No Drawing. Application July 5, 1955 Serial No.520,114

6 Claims. (Cl. 106279) This invention relates to an improved petroleumasphalt paving composition and to pavements comprising a mixture of suchcompositions and aggregate.

In this country today most asphalt pavements are prepared usingpetroleum asphalts. Petroleum asphalt is the residuum produced bydistilling ofi the lighter fractions of petroleum, including gasoline,kerosene, and other oils which tend to disperse the heavier, lessvolatile asphalt. The product frequently is blown, i.e., oxidized byblowing air through it at an elevated temperature, in order to increaseits consistency to the desired value. Many physical modifications ofpetroleum asphalt residuum are available and are well known to thoseskilled in this art. Asphalt cement, cutback asphalt, and asphaltemulsions, which are aqueous emulsions of asphalt with emulsifyingagents to assist in dispersing the asphalt, are those most usuallyencountered. Native asphalts which have been produced by naturalprocesses from petroleum by evaporation of the lighter componentsusually are not used. They must be fluxed with lighter oils before theyare suitable for paving purposes, and therefore present difierentproblems. Some so-called asphalts also are obtained from the heavierdistillates by solvent extraction. These too are somewhat different fromthe less volatile resiuum. Neither of these are contemplated for use inthis invention. Reference to asphalt hereinafter will be understood torefer to petroleum asphalt residuum only.

Over the years, through experience, a set of standards have beendeveloped, prescribing the properties desired in petroleum asphalt foruse as a paving material. These specifications do not, however, fullydefine a desirable petroleum asphalt paving material. It has been noted,for example, that many paving asphalts which have a ductility below therequirements give satisfactory pavements, some of which in factmayoutwear pavements made with asphalts which do meet the ductilityrequirements. Many paving asphalts derived from certain crudes whichmeet all of the requirements are not satisfactory in cold climates,although they are fully satisfactory in warm climates. fornia A, WestTexas, and Kansas cracked crude, for example, are unsatisfactory for usein northern states such as Ohio were the pavements have to endure wintertemperatures as low as F. and below.

Surfaces of bituminous pavements can reach minimum temperatures within afew degrees of minimum air temperatures unless the temperature rapidlydrops from a high value and then rapidly rises again the next day.Moreover, gradients as high as about 10 F. exist through a 3 inchpavement, so that the pavement must withstand not only low temperaturesbut temperature differentials within it. It should be noted that inconsidering resistance of the pavement to breaking at low temperatures,account must be taken not only of resistance to stresses from the abovedue to the vehicles using it but also of strains caused by movement ofthe subsoil, particularly in early spring. These factors tend to showthat flexibility of the pavement must be important. At the present timethere is no way of measuring the ability of a paving asphalt to resistsuch stresses. a

Asphalts derived from Cali tion.

2,877,129 Patented Mar. 10, 1959 "ice When a pavement slab is loaded,due to a stress from above or from below, it both decreases in thicknessand deflects over a limitedcircular area, assuming a cupped shape inwhich the individual particles of aggregate must be spreadsomewhatfarther apart in the horizontal direction, and somewhat closertogether in the vertical direc- The particular segment of asphalticpavement therefore must change its dimensions it is not to break. Sincethe aggregate is not deformable, such movement requires movement of theasphalt between the aggregate particles. Obviously, if the pavement isto withstand cracking under these conditions, the asphalt must retain acertain minimum degree of flexibility, and this must be retained overthe entire range of temperaturcsto which the asphalt will be subjected.This flexibility is not fixed by current standards establishedfor'petroleum paving asphalts.

Ductility is thought by some to measure flexibility, but actually itdoes not. It measures a flow property which is somewhat diflicult todefine (L; Kirschbraun, Ind. Eng. Chem. 6, 976 (1914)). i I I It issignificant that those engaged in research on the problem'of producingasphalts for use in cold climates have not reached an agreement on thecontradictory observations of asphalt ductility. -No explanation'of thecontradictions hasbeen forthcoming. It is hard to understand how apavement having a low ductility cauwithstand lowtemperatures, and yetsome do. It is suggested here that low ductility pavements which outlasthigh ductility pavements in cold climates and elsewhere may doso-because of a higher flexibility, and that this has gone unnoticedbecause flexibility has not been taken into account up until now, sinceductility gives no indication of flexibility.

Asphalt is composed primarily of asphaltenes and petrolenes, and isconsidered to be a colloidal system in which the asphaltenes constitutethe dispersed phase and the petrolenes the dispersing phase. Theasphaltenes are defined herein as that portion of asphalt which issoluble in carbon disulfide and insoluble in 50 volumes of n-pentane pervolume of asphalt. Thepetrolenes are defined herein as that fraction ofthe asphalt which is soluble in 50 volumes of n-pentane per volume ofasphalt. Asphalt can be defined in terms of other fractions, and someworkers in the field have considered asphalt to be composed ofasphaltenes, asphaltic resins, and oil fractions, with smallerquantities of waxes and othercomponents. In this concept, theasphaltenes'are considered as peptized by the asphaltic resins andthereby dispersed in the oil. The petrolene fraction ascontemplated'herein' is inclusive of both the asphaltic resin and theoil fracwhere R is .an aliphatic hydrocarbonradical, whichcan tions,together with the other components which remain in the oil phase whenthe asphalt is extracted with n.-'

pentane. e

Heretofore, it has been thought that the properties of the asphaltenefraction determined the suitability of the asphalt for paving, and thatit was this fraction which had to be modified in order to improve theasphalt for paving purposes.

In accordance withthe instant invention, .it has been determined thatthe flexibility of the asphalt at low temperatures is determined by theproperties of the petrolene fraction of the asphalt. The petroleneproperties are modified, according to the invention, by incorporatinginthe asphalt a liquid organic ester of a monocarboxylic or polycarboxylic.aliphatic fatty acid cohol.

These esters can be defined by the formula be saturated or unsaturatedand have a straight or branched chain, having from about eight to abouttwenty carbon atoms, and R is the residue of an aliphatic or cyclicalcohol whose molecular weight and structure are not critical but whichwill have an appreciable proportion of ether and/or hydroxyl groups tocarbon atoms, usually at least one hydroxyl group or ether linkage foreach six carbon atoms, or less. x and y are numbers corresponding to thenumber of carboxylic and/ or hydroxyl groups of the acid and alcoholthat are esterified. All of the carboxylic and hydroxyl groups of thepolycarboxylic acids and polyhydric alcohols need not be esterified.

Thus, R can be derived from caproic acid, lauric acid, sebacic acid,palmitic acid, myristic acid, stearic acid, oleic acid, ricinoleic acid,linoleic acid, and the mixtures of fatty acids in naturally-occurringoils and fats, such as cottonseed oil, soyabean oil, tall oil, coconutoil and tallow. The iodine value of the oil or fat should be below about140.

. R can be derived from any monohydric or polyhydric alcohol or etheralcohol, of which one or more hydroxyl groups are esterified, forinstance, glycerol, ethylene gly-' col, erythritol, pentaerythritol,polyethylene glycols of varying molecular weights, e. g., 100, 200 and400, tetrahydrofurfuryl alcohol, diethylene glycol, triethyleneglycol,.propylene glycol, butyl alcohol, and ethyl alcohol.

These esters are good asphaltene solvents and are miscible with thepetrolenes in the amounts required to reduce the flexure limit of theasphalt to below 20 F.

. The asphalt paving composition of the invention is as flexible at lowtemperatures, of the order of 20 F. and below, as the unmodifiedpetroleum asphalts are at more elevated temperatures. The flexibility ofthe asphalt of the invention, and of the pavement mix obtained bycombining such an asphalt with aggregate, may be as much as fifty timesgreater than a standard asphalt at the same temperature. This is asubstantial dilference, and, as might be expected, is accompanied by ahigh resistance to cracking at low temperatures.

This improvement in flexibility is evaluated with the aid of a specialand novel test which determines the flexure limit, a characteristicdetermined herein for the first time, of the asphalt and of the asphaltpavement. This test is important in understanding the present invention.Without such evaluation heretofore it has been impossible to determinewhether flexibility had to be improved. This test, applied to theasphalts of the invention, shows how much ester to add to reduce theflexure limit of the asphalt to 20 F. or less. The results of the testhave been correlated with actual experience by application of pavementsof the invention which pass the test to actual road construction.

The test in question, referred to hereinafter as the flexure limit test,or, simply, test, is applicable both to the asphalt and to mixtures ofthe asphalt with aggregate. It is carried out in the case of asphalt asfollows: A sample bar of the asphalt is molded. The dimensions of thebar have been standardized at 1.25 x 1.25 x 11.5 cm. The bar is broughtto the test temperature at which its flexibility is to be determined.One end is rigidly mounted in a rotatable quadrant, and the exposed endis brought sharply against the edge of an immovable object, for example,a mandrel, so placed in the path of the bar as .to apply a shearingstress thereto, and so placed that if the bar can bend at an angle of 90it will pass the object, but if it cannot bend that much it will breakon contact with the object. Six samples of each asphalt are tested at agiven temperature. The flexure limit is defined as the lowesttemperature, in F., at which all six samples will pass the surface bybending without breaking, and the term is so used in the claims.

The test is based on the following theory. Intermediate between thesolid and the gas states lie the liquid,

amorphous solid and gel states. At temperatures well above the softeningpoints, asphalts are liquid. As temperature is decreased to below thesoftening point, they gradually depart from liquid behavior, and take onmore and more a type of elastic behavior characteristic of gels. Atstill lower temperatures they become amorphous solids, incapable offlowing under stress except at very slow rates, and exhibiting brittlefracture when overstressed. In the case of asphalt, the transition froma gel-like liquid which retains appreciable flexibility to a brittlesolid occurs within a relatively short temperature range. Atsuccessively lower temperatures, as the transition progresses, thetendency of the asphalt to break increases as it is forced to bendaround the fixed radius, and eventually the asphalt reaches the flexurelimit, at which fracture occurs. The test thus fixes the flexure limitat the temperatures at which the flexible gel-like state passes into thebrittle state. The existence of this rather sharply defined flexurelimit makes it possible to define rather precisely the low temperatureproperties of a paving asphalt.

The flexure limits of several of the most commonly met asphalts aregiven in the table below:

TABLE I Penetration at 77 F.

Flexure Izimit,

Asphalt from Crude California A Illinois Cracked Illinois N KansasCracked.

Smackover. Texas Venezuelan.

California B West Texas Panuco-Mcxican These asphalts, which have knownservice records, show trends in the flexure limit which correspond totheir performance at low temperatures. The Texas and Mexican asphaltsare considered good paving asphalts in cold climates, and they have thelowest flexure limits in the group. The asphalts which are known to beworst in cold climates have the highest flexure limits; these are theWest Texas, California A and the various cracked asphalts. It will benoted that the lowest limit is 31 F. In contrast, the paving asphaltcompositions of the invention have flexure limits of 20 F., maximum, andpreferably 15 F. or below.

In accordance with the invention a paving asphalt, such as any of theasphalts listed above, is blended with an ester as defined above havingcertain specified physi-.

cal properties in an amount within the range from 10% to 40%, preferablyfrom 15% to 30%, by weight of the asphalt blend sufiicient to give thedesired low flexure limit.

The ester must meet the following requirements:

(1) It must be a liquid at temperatures at least as low as theflexurelimit required for the asphalt blend, preferably at least 5 F. less thanthe flexure limit, and in any event below 20 F.

Y (2) A flash point (Cleveland Open Cup) of at least 400 F., andpreferably at least 440 F.

(3) 'A viscosity no higher than 20 poises at 77 F., and preferably lessthan 5 poises at that temperature.

(4) A viscosity index of not less than 40, and preferably at least 60.

Typical esters are glycerol monolaurate, glycerol monooleate, propyleneglycol monolaurate, diethylene glycol dioleate, Cellosolve ricinoleate(ricinoleic acid ester of diethylene glycol), polyethylene glycol 200monolaurate, polyethylene glycol di-Z-ethyl hexoate, diisooctylsebacate, tetrahydrofurfuryl oleate, butyl Cellosolve oleate (oleic acidester of butyl ether of diethylene glycol), polyethylene glycol 400tallate, methyl tallate, and the naturally-occurringfats and oils havingan iodine value below about 140, such as soyabean oil and cottonseedoil.

If desired, the ester can be used together with a hydrocarbon oil whichis primarily parafiinic in nature, which has a viscosity index of atleast 40, and which meets the other requirements mentioned for theester. These are solvents for the petrolene s, and also are effective tolower the flexure limit.

The hydrocarbon oil can be solvent extracted and conventionally refinedneutral oils, bright stocks, vacuumdistilled cylinder oils, gas oils,dewaxed gas oils, wax slops fractions, and the like.

The proportions of the oil and ester are not critical, inasmuch as bothare effective for the same purpose. However, usually the ester will bein a major proportion, although mixtures containing as little asone-third ester and less are, of course, satisfactory. I

It will be appreciated that the amounts of ester and mixtures thereofwith the hydrocarbon oil depend upon the viscosity, softening point andother properties desired in the finished product, but the amount will'beselected within the 10 to 40% range stated to produce an asphalt blendhaving the desired flexure limit of 20 F. or below.

After addition of the ester and/or hydrocarbon oil, the asphalt, ifnecessary, will be brought to a 77 F. penetration within the pavingrequirements. Of course, if the mixing is done after oxidation it willbe necessary to oxidize the asphalt to a lower penetration. than isdesired in order to meet the final penetration:requirement, inasmuch asthe hydrocarbon oil and/ or ester will ,increase the penetration. Forpaving purposes, .the as phalt blend should have a 77 F. penetrationwithin the range from 40 to 200.

As is well known, asphalts which aretoo soft can be brought to a higherconsistency by blowing with air at a temperature within the range of 375to 500 F. This is a standard procedure and is fully set forth in theliterature. Oxidation is continued until penetration has increased tothe desired value. The ester and the hydrocarbon oil do not interferewith the oxidation, although there is a possibility of some loss of theester or hydrocarbon oil during oxidation if it has a low enough boilingpoint. To avoid this, the ester and/or oil can be added after oxidationof the asphalt, as has been stated.

The ester and/or mixture thereof with the hydrocarbon oil can beincorporated in the asphalt by any desired means. It is preferable thatthe asphalt be fluid, and that the blending be accompanied withsufficient mixing to insure uniform distribution therein. Conventionalmixing equipment is satisfactory. If the ester and/ or oil is addedbefore the asphalt is air-blown, the air-blowing of the fluid asphalt atan elevated temperature will insure The asphalt composition of theinvention is intended for use in the preparation of conventionalasphalt-aggregate paving mixes. These are well known, and a detaileddescription therefore is unnecessary. I

Asphalt pavements for road construction are prepared from 4 to 15%asphalt and the remainder mineral aggregate or filler. The mineralaggregate and filler is selected from materials such as limestone, slag,gravel, and the like. The aggregate must meet certain specifications asto the size range of the particles, depending upon whether the pavementis to be coarse or dense, and may range from coarse sizes of inch indiameter down to dusts of 200 mesh and less. Details are given inchapters II and IV of the Asphalt Handbook (1947) published by TheAsphalt Institute, College Park, Maryland, the disclosures of which arehereby incorporated by reference.

Asphalt paving mixes may be divided into two general classes, i. e.,hot-mix and cold-mix. The cold-mix is prepared at ambient temperaturesby the mixing of mineral aggregates with cut-back asphalts. Cut-backasphalt is a term used to describe conventional asphalt compositions towhich a solvent such as petroleum naphtha has been added in order torender the asphalt fluid at ordinary temperatures. After application ofcold-mix to a road, the solvent evaporates, leaving behind a hardasphalt surface. While cold-mix is satisfactory in certain specializedapplications, it is believed by the paving industry that the mostsatisfactory roads are constructed with a hot-mix, and this invention isconcerned particularly with the manufacture of a hot-mix.

Hot-mix asphalt paving mixtures are generally produced at an asphaltpaving plant. Measured quantities of aggregate and asphalt cement, bothat about a temmixing usually accomplished in a short time, on the orderof two to five minutes. The hot-mix is then dumped from the mixer intotrucks or into storage bins. The trucks are usually insulated so thatthe mix will not lose its temperature while being transported to theactual paving site. y

The following examples are illustrative.

Examples 1 to 16 A sample of pipestill bottoms with a 77 F. penetrationin the range of 200 to 280 was oxidized by heating. while blowing withair at 450 to 460 F. toa viscosity as identified in the table below, inthe amounts indicated,-

to the viscosity stated in the table. Each of the additives had aviscosity, flash point and fire point within the ranges adequate mixing.e n heretofore- TABLE IA Ester Asphalt Example Ooncen- N tratlon, EsterPenetration Flexure 0 Percent Vis Flash, Fire, Vis., Flash, Fire, Soft.Limit,

77 F. F. 300 F. F. F. pt. F F.

None 16 120 33 Soyabean oil- 80 102. 5 7 Cottonseed oil 46 14 Diisooctylsebacate l 92 106 -3 Tetrahydrofurfuryl oleate 158 102 14 Polyethyleneglycol dl-lrethyl hexoate- 134 104 -9 Dlethylene glycol oleate 104 11Polyethylene glycol 200 monolaurate 104 2 Butyl Cellusolve oleate. 76110 3 Glycerol monooleate- 65. 5 100 4 Propylene glycol monolaurate. 69109 7 Glycerol laurate S 48 114 12. 5 Glycerol monooleate- 65. 5 106 8.5

. Do 76.5 106, 1.6 Polyethylene glycol 400 tallate. t 58 127 11vPolyglycol 300 tallate 1. 39 65 114 perature of 300 F., are dumped intoa mixer, and the Y 7 The above data-show that a wide variety of fattyesters are useful to adjust the flex-ore limit to below 15 F. and,infact, a limit as l'ow as -14 F. is obtainable (15x ample 5 Examples 17and 18- Two asphalts were prepared. using the same pipestill bottoms.employed in Examples 1 to 1.6. In. one (Example 17) hethyl. tallate was.added before. oxidation of the pipestillbottoms. In the other, 27%.methyl tallate (Example 18) was added after the pipesn'll. bottoms had.been oxidized to a penetration of 1.0 at 77 F Example 18 had afiexurelimit of 2 F., whereas Example 17 had a flexure limit of 30. Thisdifierence was due to volatilization of the methyl tallate during theoxidation in Example 17. The data show that in the case of more volatileesters it is necessary to incorporate the ester after the asphalt hasbeen brought to the desired penetration. However, whether the ester isadded before or after the oxidation is immaterial in obtaining thedesired fiexure limit, as Examples 1 to 16 show.

Examples 19 to 23 2900 gallons of conventionally-refined neutral oil,300 SSU at 100 F., and 1400 gallons of soyabean oil were charged. to atank at about 60 F., and pipestill bottoms (viscosity at 300 F., 67Furol seconds, penetration 77 F., 195; 19.9% asphaltenes; petroleneviscosity at 77 F. 2078 poises, and at 100 F. 368 poises; petroleneviscosity gravity constant 0.862) was added. The batch composition was31.1 volume percent of the mixed neutral oil soyabean oil, and 68.9volume percent of the pipestill bottoms. The mix was heated to 370 F.,airblowing was started, and the batch oxidized past the desired endpoint of 130 Furol seconds at 300 F., the viscosity going from 121 to157 seconds in one hour.

275 gallons of the neutral oil-soyabean oil mixture were then added,followed by 880 gallons of the pipestill bottoms, and the batch finishedby further oxidation to the viscosity given in Table II. The tablecompares the properties of this material with a standard 108 penetrationasphalt and a standard 70/80 penetration asphalt.

TABLE II Example Example Example No. 19 o. 20 o. 21

Furol Viscosity at:

350 F 41. 4 33. 3 47.7 68. 4 126.8 88. 2 136. 5 245. 2 250 F 773. 4 324.2 525 Softening Point (R & B), F-.." 127 110 118 Penetration:

11550 g 5 see 270 345 340 11050 g.-5 sec... 161 269 201 77100 g.--5 Sec110 111 80 -200 g.60 sec 69 42 13 Ductility:

775 m./m1n.- 22. 7, 19. 100+ 100+ 60-5 cm./min- 8. 5 100+ 100+ FlexureLimit, F" 0 22. 5 32. 5 Thermal Expansion Transition Temp, F.-. 14 25Coeflicient, 111./in./ F 8. 0Xl0- 6. 2X10 8. 9X10 Standard Index, 140-50p. s. 1.:-

72 hrs 19 5 1 Flash Point (000), F 490 600 625 Fire Point (COO), F- 565600 625 Loss on Heating, 32

5 hrs, percent 0. 14 0. 004 0.013 Pen. on Residue 101 101 70 SpecificGravity:

Homo Homo Home 77 224 1, 960 17, 585 Petrolene, 100 Viscosity, GravityConstant 0. 849 0. 843 0. 817

8 26') was prepared starting with a 107 penetration base containing 10percent of Rubarite, a synthetic rubberadditive. These asphalts had thefollowing properties:

TABLE III Example Example N o. 22 No. 23

Viscosity, Furol, at:

350 325 F. 86 154 300 146 310 276F. 271 440 250 F 577 986 R dz B Soft.Pt., F 115 117.5 Penetration:

5, 50-5 100, 60-5. '202 190 77, 100-5. 87. 32, 200-60 25 25 Ductiiity':

77-5 elm/min. 77; 5 cm./m1n-. Flexure Limit, F-.- 30 20' Stain Index, 11 Flash Point (000), F... 570 610 Specific Gravity, 77 1.033 1. 045 Losson Heating, 325+50 0. 054 0. 008 Pen. on Residue 82 80 PercentAsphaltenes 28. 3 23. 4 Petrolene Viscosity:

0 F 391 1, 330 F 2, 780 9, 935 Petrolene, Specific Gravity, 100 0.985,0. 958; Petrolene, 100 Viscosity, Gravity Constanta. 0. 91 4 ,0. 828

These five asphalts (Examples 19 to 23) were subjected to rheologicaltests using test methods developed by the Franklin InstituteLaboratories for Research and: Development as part of the NationalAsphalt Research Center Program and described in NARC Reports Rel, R-Z,R-4 and R-S. According to these tests the asphalt of the invention.(Example 19) had a lower shear modulus of elasticity throughout theentire temperature. range, was more easily sheared and behaved more likea liquid at low temperatures than Examples 22 and 23. The viscositycoeflicient was not improved at the. extreme low temperature but ataboveabout 10 I it is lower for the asphalt of the invention.

The asphalts were tested for variation in impact strength vs.temperature. All tests were made using A x /2" x 6" bars prepared bycasting from the molten condition. The bars were supported on roundedsupports separated by 1%", and a 50 gram striker guidedby wires wasallowed to fall from increasing heights. until the approximate heightfor breaking was bracketed. The height was then increased until sixsuccessive samples were broken at the same drop height. The data showedthat the asphalt of the invention was. far super.-. ior in impactresistance to all of the others studied at all temperatures from -15 F.up.

The modulus of elasticity vs. temperature was measured using an AmericanInstrument Co. "Modulimeter mounted in a constant temperature box: Barsvx /2 x 6" were used as test specimens. The asphalt of the invention hada lower modulus of elasticity throughout the temperature range studied(0-40 F.) than any of the other asphalts.

In order to demonstrate that the same results are obtainable when theasphalts are mixed with aggregate, the above tests were repeated usingpavement mixtures prepared as follows: 75 grams of 40-80 mesh lake sandand 15 grams of limestone dust were weighted out and each portion mixedand placed in a 325 F. oven along with a mold for a /2" x /:a" .x 5" barand the asphalt to be used. When the asphalt was completely melted, 10grams were added to the hot sand-limestone dustf blend and theingredients mixed well with a putty knife. 40 grams of the hot aggregatewere placed in the mold and the mold subjected to 6000 p. s. i. g.hydraulic pressure in a Carver Laboratory press and allowed to come toroom temperature.

In the Modulimeter test the asphalt of the invention.

9 flexed theagre atest at all temperatutes'and'rthe" changes in moduluselasticity from 35? F. to F. were & that of the standard 108penetratic'ni asphaltand that of the others. The asphalt of theinvention showed up well under'impact and constant force deformation, aswell. The sheet-asphalt mixture containing the asphalt of theinventionwill withstand an impact from a height 3% times greater than any otherasphalt at 20 and 30 F.

Examples 24 to 29 A group of six asphalts were prepared in order toobtain Weathering data. These were compared with the blank composed ofthe asphalt base without the additive. The same pipestill bottoms ofExamples 1 to 16 were employed, and this was mixed with cottonseed oil,soyabean oil, solvent extracted neutral oil (300 SSU at 100 F.) andmixtures of solvent extracted neutral oil and cottonseed oil in theamounts indicated in Table IV below.

The test was carried out on a mixture obtained by heating a portion ofthe asphalt to 300 F. and thoroughly mixing it by hand with standardOttawa sand heated to the same temperature in an amount such that theasphalt was 1.6% by weight of the mix. Each batch was divided into threeportions and placed uncompacted in pans. One portion is retained as acontrol and the other two portions are placed on the roof of a building.One sample is examined after three months exposure and the other aftertwelve months. Extraction and recovery of the asphalt is carried out bythe A. S. T. M. Abson method.

The weather and test results are given in the table below.

and aliquid ester having an iodine valuebelow 140 of an aliphatic fattycarboxylic acid having from about nine to about twenty-one carbon atomsand a saturated nonaromatic alcohol characterized by a softening pointbelow the flexure limit of the asphalt composition, a flash point(Cleveland Open Cup) of at least 400 F., a viscosity-at 77 F; below 20poises, and a viscosity index above 40, the said ester being present inan amount within-the range from about 10% to about to reducethe"flexure'- limit of the asphalt to below 20 F. iv 1 2. A pavingasphalt composition having a flexure limit below 20 F. consistingessentially of a petroleum residuum asphalt having a flexure limit above20 F. and a liquid ester having an iodine value below 140 of analiphatic fatty carboxylic acid having from about nine to abouttwenty-one carbon atoms and a saturated nonaromatic alcohol, and aprimarily paraffinic liquid mineral hydrocarbon oil, each characterizedby a softening or pour point below the fiexure limit of the asphaltcomposition, a flash point (Cleveland Open Cup) of at least 400 F., aviscosity at 77 F. below 20 poises, and a viscosity index above 40, thesaid ester and oil being present in a total amount within the range fromabout 10% to about 40% to reduce the flexure limit of the asphalt tobelow 20 F.

3. A process for preparing a paving asphalt composition having a flexurelimit below 20 F., which consists essentially of the step ofincorporating in a petroleum residuum asphalt having a flexure limitabove 20 F., a liquid ester having an iodine value below 140 of analiphatic fatty carboxylic acid having from about nine to abouttwenty-one carbon atoms and a saturated non- TABLE IV Example No 24 2526 27 28 29 15% Solvent 20% Solvent extracted extracted 30% Solventneutral oil, bright stock, extracted Control 30% Cot- 30% Soya- 140 SSUat 78 SSU at neutral oil, tonseed on been 011 100 F., 10% 210 F., 10%300 SSU at Cottonseed Cottonseed 100 F.

Penetration 77 F.:

0rlginal 135 135 102 110 98 After a months. 41 111 127 88 100 72 After12 months 31 69 10a 82 56 Percent Decrease 38 49 24 20 45 43 Penetration32 F.:

Original -1 16 73 62 66 78 After 3 months- 10 55 a4 60 68 59 After 12months 19 45 46 47 5s 50 Percent Decrease. 19 38 54 24 20 36 R A: BSoftening Point:

Original 129 103 131 144 Alter a months 137 122 113 141 143 172 146 138149 13 26 4s 16 22 32 100+ 100+ 100+ 27 10 5 26.5 86 100+ 11 6 3 After12 months 5 30 36 9 4 3 Percent Decrease 95+ 70+ 64+ 67 60 45 The datashow that the mixture of solvent extracted aromatic alcoholcharacterized by a softening point below neutral oil and cottonseed oilis quite satisfactory. The the fiexure hmit of the asphalt composition,a flash point mixtures containing the solvent extracted neutral oil and(Cleveland Open Cup) of at least 400 F., a viscosity at solventextracted bright stock change more slowly than 77 F. below 20 poses, anda viscosity index above 40, the blank and the other samples. Softeningpoints also 5 :m an amount within the range from about 10% to aboutincrease for these materials but less rapidly than the 40% to reduce theflexure limit of the asphalt to below others.

A blend of petroleum oil and fatty oil is the best from A Process for Pfp a P g asphalt P S On the standpoint of weathering. Ihavmg a flexurel1m1t below 20 F., WhlCh consists All proportions and percentages in thespecification and 70 ssentially of the step of incorporating in apetroleum claims are by weight of the final asphalt composition.

I claim:

1. A paving asphalt composition having a flexure limit below 20 F.consisting essentially of a petroleum residuum asphalt having a fiexurelimit above 20 F., a liquid ester having an iodine value below 140 of analiphatic fatty carboxylic acid having from about nine to abouttwenty-one carbon atoms and a saturated nonresiduum asphalt having aflexure limit above 20 F. 7 aromatic alcohol, and a primarily paraffinicliquid mineral hydrocarbontoil each characterized by a softeningor'pour: POint below thefiilexure limit" o'fi the asphalt composition, aflash point- (Clevclanditopen Cup.) oftat; least- 4001 F1, a viscosityat 7'7':" -F:-belovg'ZQ-poises, and aoviscosity index above 4V0, he.said esten and; Qflmbfiing present-in a total' amount within the range,-from abont =10%;to,.about 40 to reduce the "flx1 1re1imi't'0fhhevasphalt-ato below 20 F.-

51. A process in accordance with cla ingt3:.which,includes.- Qxidizingthe asphalt to a penetration at 737-5- F. within the range of about 40to about 200.

6 A process in accordance with cl,a ir n 4 which-includes oxidizing theasphalt to. a penetration at 77 F. within the range of about; 40 toabout20.0,

References Cited the file of patent ss' fA ifit BAIENTIIS? ,I uly1.24.1927- UNITED STATES PATENT OFFIll l CERTIFICATE OF CORRECTION March10 1959 Patent No. 2,877,129

Harley F. Hardman appears in the-printed specification It is herebycertified that error correction and that the said Letters of the abovenumbered patent requiring Patent should read as corrected'below.

Column .1, line 36, for "re'siuum" read residuum column 6, line 36,after "mixing" insert is column '7, line 8, for "hethyl" read me'thylcolumn 8-, line 65 for "weighted" read weighed Signed and sealed this7th day ofJulyl959.

(SEAL) Attest: I

KARL E. AXLINE I ROBERT c. WATSON v Commissioner of Patents AttestingOfiicer

1. A PAVING ASPHALT COMPOSITION HAVING A "FLEXURE LIMIT" BELOW 20* F.CONSISTING ESSENTIALLY OF A PETROLEUM RESIDUUM ASPHALT HAVING A "FLEXURELIMIT" ABOVE 20* F. AND A LIQUID ESTER HAVING AN IODINE VALUE BELOW 140OF AN ALIPHATIC FATTY CARBOXYLIC ACID HAVING FROM ABOUT NINE TO ABOUTTWENTY-ONE CARBON ATOMS AND A SATURATED NONAROMATIC ALCOHOLCHARACTERIZED BY A SOFTENING POINT BELOW THE "FLEXURE LIMIT" OF THEASPHALT COMPOSITION, A FLASH POINT (CLEVELAND OPEN CUP) OF AT LEAST 400*F., A VISCOSITY AT 77* F. BELOW 20 POISES, AND A VISCOCOSITY INDEX ABOVE40, THE SAID ESTER BEING PRESENT IN AN AMOUNT WITHIN THE RANGE FROMABOUT 10% TO ABOUT 40% TO REDUCE THE "FLEXURE LIMIT" OF THE ASPHALT TOBELOW 20* F.